Prediction of Brinell hardness distribution in cold formed parts

The objective of this study is to predict the Brinell hardness distribution in cold formed parts by relating the plastic strains found by finite element (FE) analysis to hardness. Based on the material's plastic flow curve, an analytical relation was established between the plastic strain induced in the metal during cold working and its Brinell hardness so that its hardness can be determined from numerically obtained plastic strains without producing the part and taking measurements. In order to verify the model developed in this study, cold extrusion experiments were performed on samples made of two different metals at five different extrusion ratios. These samples were cut, and at their centers Brinell hardness measurements were taken, which were then compared with the analytical predictions. The results of the analytical model compared quite well with the data obtained from experiments. The model was also verified by comparing its predictions with the experimentally determined values of hardness reported by previous researchers. The results showed that within the applicable range of Brinell hardness test, which covers a great percentage of hardness levels resulting from cold forming operations, the analytical model can reliably be used.